大庆油区葡萄花主力油层聚合物交替注入对驱油效果的影响

Effect of Polymer Alternative Injection on Oil Displacement Efficiency of Putaohua Main Reservoir in Daqing Oilfield

为改善杏树岗油田葡Ⅰ1数3油层动用不均匀、聚合物沿高渗透层低效循环的现象,设计三管并联岩心注入实验,研究了聚合物相对分子质量、浓度和注入方式(单独注入和交替注入)对采收率的影响,用数值模拟方法对交替注入周期进行了优选。结果表明:随聚合物相对分子质量和浓度的增加,岩心采收率逐渐增加;单一聚合物驱可以有效动用高渗透层,但驱替低渗透层效果较差;交替注入聚合物的平均采收率比单一聚合物驱提高3.3%数5.47%,先注入大分子量聚合物段塞后注入小分子量聚合物段塞的驱油效果好于相反顺序段塞的驱油效果。数值模拟结果显示,交替注入时间间隔过长不利于控制流度,时间间隔过短容易造成黏度损失,耗损较大能量,不利于驱油,该区块最佳交替注入周期为3个月,可提高采收率11.68%。

In order to improve the phenomenon that the producing degree of Pu Ⅰ 1—3 layers was uneven and the polymer circulated along high permeability layers inefficiently in Xingshugang oilfield,three tubes parallel core injection experiment wasdesigned. The impact of polymer relative molecular mass,concentration and injection mode（single injection and alternative injection）on the recovery was researched,and the alternative injection cycle was optimized using numerical simulation method.The results showed that with increasing relative molecular mass and concentration of polymer,the core recovery increased. Single polymer could effectively flood the high permeability layer,but had poor effect in low permeability layer. The average recovery ratio of alternative injection polymer flooding was 3.3% —5.47% higher than that of single injection polymer flooding. The oil displacement effect of polymer flooding with first injection of high molecular weight polymer slug and then small molecular weight of polymer slug was better than that of reverse injection order polymer slug. The numerical simulation results showed that it was not conducive to control fluidity if the alternate injection interval was too long,while it was easy to cause viscosity loss if the time interval was too short,which resulted in the loss of a large amount of energy and was not conducive to oil displacement. So the best alternative injection period was 3 months,which could increase the recovery ratio by 11.68%.